Split out the non-ARM specific portions of SYS_ISTTY to a
reusable function. This handles all GuestFD.
Add a common_semi_istty_cb helper to translate the Posix
error return, 0+ENOTTY, to the Arm semihosting not-a-file
success result.
Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
a221247430